Spatial features (e.g., roads, rivers, land parcels, buildings, rooms, pieces of furniture) may be represented by geometries. Geometries may be stored in objects (e.g., SDO_GEOMETRY objects). Some spatial features are collections of other spatial features. For example, a city may be viewed as a collection of buildings, roads, open spaces, and so on. A building may in turn be viewed as a collection of rooms, hallways, doorways, and so on. A data type may describe what a feature may include. An instance of a data type may or may not include everything described in a data type. Thus, a feature instance may or may not include everything described in a feature type.
A feature instance may be an object representing one specific, actual building. The feature instance may have spatial content. The spatial content may be hierarchical (e.g., building, room(s), walls, doors). The hierarchical content may have descending degrees (e.g., complex solid, simple solid, complex surface, simple surface, line, point). Conventionally, feature data has not been indexed on spatial content.
The Web Feature Service Implementation Specification (WFS 1.0.0) proposed interfaces for describing data manipulation operations on geographic features. The proposed interfaces use HTTP to support the interfaces and data manipulation operations. A Web Feature Service (WFS) request includes a description of a query or a data transformation operation (e.g., create/update/delete) to be applied to an instance(s) of a web feature. The request may be generated on a client and posted to a Web Feature server using the distributed HTTP. The Web Feature server may parse and execute the request. An instance of a web feature may have spatial content. This spatial content may be hierarchical, meaning that a feature instance may have a collection of spatial collection content. Conventionally, this WFS feature data may not have been indexed and thus it may have been difficult, if possible at all, to search based on WFS feature data, which may have limited, or made more complicated, the processing of WFS requests.